One works by inhibiting the activity of a viral enzyme called reverse transcriptase.

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Dr Wilson and his colleagues have discovered that the complex finds its way to the active site of a viral enzyme known as reverse transcriptase.

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It belongs to a class of drugs called reverse transcriptase inhibitors.

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It was approved in the USA last summer where it has become the only non-nucleoside reverse transcriptase inhibitor (NNRTI) - a class of HIV drug - to be included as a first line option in national guidelines.

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